1. Field of the Invention
The present invention relates to image projection systems and image projection methods. More specifically, the present invention relates to an image projection system and an image projection method for projecting images on an image projection region from a plurality of image projection sections.
2. Description of the Related Art
A stereolithography apparatus that produces a three-dimensional shaped object by using a photo-curable resin in liquid form is conventionally known. A photo-curable resin has the property of being cured with irradiation of light such as visible light or ultraviolet light.
As such a stereolithography apparatus, a “lifting type” stereolithography apparatus, for example, is used. In the lifting type stereolithography apparatus, three-dimensional shaping is performed by sequentially stacking photo-curable resins each cured into a given shape.
In the lifting type stereolithography apparatus, a transparent plate is used as a bottom wall of a container that stores a photo-curable resin in liquid form. A shaped object holing plate serving as a base for a three-dimensional shaped object is disposed inside the container. With irradiation of light from below the transparent plate, the photo-curable resin is cured to have a given liquid layer thickness at a lower surface of the shaped object holding plate. Thus, a cured layer having a given liquid layer thickness is provided at the lower surface of the shaped object holding plate.
Then, the cured layer cured between the shaped object holding plate and the transparent plate is peeled off from the transparent plate serving as the bottom wall of the container, and the shaped object holding plate is raised by a given liquid layer thickness.
Subsequently, with irradiation of light from below the transparent plate, the photo-curable resin is cured by a given liquid layer thickness to provide another cured layer in addition to the cured layer provided at the lower surface of the shaped object holding plate.
These operations are repeated in sequence, thus providing a three-dimensional shaped object.
With the use of the lifting type stereolithography apparatus, cured layers each having a desired shape are sequentially stacked by repeating the above-described operations in sequence. As a result, a three-dimensional shaped object having a desired shape can be produced.
In such a stereolithography apparatus, a given image has to be projected on an interface between a bottom wall of a container and a photo-curable resin layer from a projector which is an image projection section, in order to allow a photo-curable resin stored in the container to be cured into a desired shape.
Such a stereolithography apparatus may use an image projection system in which an image representing a three-dimensional shaped object is formed from images projected on an image projection region from a plurality of projectors. Note that the term “image projection region” refers to a region of an image projection surface where an image is projected. In the above-described stereolithography apparatus, the image projection surface is the interface between the bottom wall of the container and the photo-curable resin layer.
In such an image projection system, a plurality of projectors are used in accordance with a size of an image projection region. In this case, the image projection region is divided in accordance with a size of an input image of each projector. Images are projected on the divided regions from different projectors.
An image projected from each projector is an image obtained by dividing, in accordance with each of the divided regions, a single image projected on the entire image projection region. Hereinafter, a single “image projected on the entire image projection region” will be referred to as a “large image”, and an “image obtained by dividing the large image in accordance with each of the divided regions” will simply be referred to as a “divided image”.
The following description will be provided for an example illustrated in FIGS. 16A and 16B. In this example, a large image “A” is projected on an image projection region R having dimensions of 136.1 mm (7716 pixels) by 121 mm (6862 pixels) with the use of two projectors each capable of projecting an image of 1366 by 768 pixels.
First, as illustrated in FIG. 16A, the image projection region R is divided into a first sub-region S1 and a second sub-region S2. The first sub-region S1 is an upper sub-region with respect to a center of the image projection region R in a longitudinal direction Y, and the second sub-region S2 is a lower sub-region with respect to the center of the image projection region R in the longitudinal direction Y. The first sub-region S1 is set as a region where an image is to be projected from a first projector. The second sub-region S2 is set as a region where an image is to be projected from a second projector.
Subsequently, as illustrated in FIG. 16B, the large image A is divided into a divided image P1 to be located in the first sub-region S1 and a divided image P2 to be located in the second sub-region S2. The divided image P1 is set as an image to be projected from the first projector. The divided image P2 is set as an image to be projected from the second projector.
Then, the divided image P1 is projected on the first sub-region S1 from the first projector, while the divided image P2 is projected on the second sub-region S2 from the second projector. As a result, the large image A is projected on the image projection region R.
In such an image projection system, installation positions and/or orientations of the projectors must be adjusted so that each divided image is projected in a proper state on a target sub-region of an image projection region.
As used herein, the term “proper state” refers to a state in which the divided image is projected on the target sub-region without any distortion in shape from the projector (image projection section).
As a technique for adjusting projector position and/or orientation, a technique disclosed in Japanese Patent No. 4002983, for example, is known.
Japanese Patent No. 4002983 discloses a technique for providing a mechanism for adjusting projector position and/or orientation. In the technique disclosed in Japanese Patent No. 4002983, an image projected from a projector is projected in a proper state on an image projection region of an image projection surface.
However, when an image projection system installed on a stereolithography apparatus is provided with a mechanism for adjusting projector position and/or orientation, the image projection system is increased in size. As a result, the stereolithography apparatus on which the image projection system is installed is undesirably increased in overall size.
Moreover, when an image projection system is provided with a mechanism for adjusting projector position and/or orientation, fabrication cost for the image projection system is increased. As a result, fabrication cost for a stereolithography apparatus on which the image projection system is installed is undesirably increased.
If an image projected from a projector is corrected so that the image is in a proper state in a target sub-region of an image projection region without providing a mechanism for adjusting projector position and/or orientation, a large image is projected in a proper state on the image projection region without causing the above-mentioned problems.